From 06f9183f15e6acbde86b86d5f8be36ac8cfaa9bc Mon Sep 17 00:00:00 2001
From: Ben Lesh <ben@benlesh.com>
Date: Fri, 15 Mar 2019 10:24:58 -0700
Subject: [PATCH] fix(race): better typings (#4643)

- Actually accept other `ObservableInput` types (Promises, etc)
- Fixes issue where TypeScript would complain when you tried to subscribe to a race between to Observable types.

Fixes #4390
Fixes #4642
---
 spec-dtslint/observables/race-spec.ts | 151 +++++++++++++++++---------
 src/internal/observable/race.ts       |  29 +++--
 2 files changed, 120 insertions(+), 60 deletions(-)

diff --git a/spec-dtslint/observables/race-spec.ts b/spec-dtslint/observables/race-spec.ts
index 805d8a6137..e31f1465f2 100644
--- a/spec-dtslint/observables/race-spec.ts
+++ b/spec-dtslint/observables/race-spec.ts
@@ -5,65 +5,116 @@ it('should infer correctly with 1 parameter', () => {
   const o = race(a); // $ExpectType Observable<number>
 });
 
-it('should infer correctly with multiple parameters of the same type', () => {
-  const a = of(1);
-  const b = of(2);
-  const o = race(a, b); // $ExpectType Observable<number>
-});
+describe('race(a, b, c)', () => {
+  it('should infer correctly with multiple parameters of the same type', () => {
+    const a = of(1);
+    const b = of(2);
+    const o = race(a, b); // $ExpectType Observable<number>
+  });
 
-it('should support 2 parameters with different types', () => {
-  const a = of(1);
-  const b = of('a');
-  const o = race(a, b); // $ExpectType Observable<string> | Observable<number>
-});
+  it('should support 2 parameters with different types', () => {
+    const a = of(1);
+    const b = of('a');
+    const o = race(a, b); // $ExpectType Observable<string | number>
+  });
 
-it('should support 3 parameters with different types', () => {
-  const a = of(1);
-  const b = of('a');
-  const c = of(true);
-  const o = race(a, b, c); // $ExpectType Observable<string> | Observable<number> | Observable<boolean>
-});
+  it('should support 3 parameters with different types', () => {
+    const a = of(1);
+    const b = of('a');
+    const c = of(true);
+    const o = race(a, b, c); // $ExpectType Observable<string | number | boolean>
+  });
 
-it('should support 4 parameters with different types', () => {
-  const a = of(1);
-  const b = of('a');
-  const c = of(true);
-  const d = of([1, 2, 3]);
-  const o = race(a, b, c, d); // $ExpectType Observable<string> | Observable<number> | Observable<boolean> | Observable<number[]>
-});
+  it('should support 4 parameters with different types', () => {
+    const a = of(1);
+    const b = of('a');
+    const c = of(true);
+    const d = of([1, 2, 3]);
+    const o = race(a, b, c, d); // $ExpectType Observable<string | number | boolean | number[]>
+  });
 
-it('should support 5 parameters with different types', () => {
-  const a = of(1);
-  const b = of('a');
-  const c = of(true);
-  const d = of([1, 2, 3]);
-  const e = of(['blah']);
-  const o = race(a, b, c, d, e); // $ExpectType Observable<string> | Observable<number> | Observable<boolean> | Observable<number[]> | Observable<string[]>
-});
+  it('should support 5 parameters with different types', () => {
+    const a = of(1);
+    const b = of('a');
+    const c = of(true);
+    const d = of([1, 2, 3]);
+    const e = of(['blah']);
+    const o = race(a, b, c, d, e); // $ExpectType Observable<string | number | boolean | number[] | string[]>
+  });
 
-it('should support 6 or more parameters of the same type', () => {
-  const a = of(1);
-  const o = race(a, a, a, a, a, a, a, a, a, a, a, a, a, a); // $ExpectType Observable<number>
+  it('should support 6 or more parameters of the same type', () => {
+    const a = of(1);
+    const o = race(a, a, a, a, a, a, a, a, a, a, a, a, a, a); // $ExpectType Observable<number>
+  });
+
+  it('should return {} for 6 or more arguments of different types', () => {
+    const a = of(1);
+    const b = of('a');
+    const c = of(true);
+    const d = of([1, 2, 3]);
+    const e = of(['blah']);
+    const f = of({ foo: 'bar' });
+    const o = race(a, b, c, d, e, f); // $ExpectType Observable<{}>
+  });
 });
 
-it('should return {} for 6 or more arguments of different types', () => {
-  const a = of(1);
-  const b = of('a');
-  const c = of(true);
-  const d = of([1, 2, 3]);
-  const e = of(['blah']);
-  const f = of({ foo: 'bar' });
-  const o = race(a, b, c, d, e, f); // $ExpectType Observable<{}>
+describe('race([a, b, c])', () => {
+  it('should infer correctly with multiple parameters of the same type', () => {
+    const a = of(1);
+    const b = of(2);
+    const o = race([a, b]); // $ExpectType Observable<number>
+  });
+
+  it('should support 2 parameters with different types', () => {
+    const a = of(1);
+    const b = of('a');
+    const o = race([a, b]); // $ExpectType Observable<string | number>
+  });
+
+  it('should support 3 parameters with different types', () => {
+    const a = of(1);
+    const b = of('a');
+    const c = of(true);
+    const o = race([a, b, c]); // $ExpectType Observable<string | number | boolean>
+  });
+
+  it('should support 4 parameters with different types', () => {
+    const a = of(1);
+    const b = of('a');
+    const c = of(true);
+    const d = of([1, 2, 3]);
+    const o = race([a, b, c, d]); // $ExpectType Observable<string | number | boolean | number[]>
+  });
+
+  it('should support 5 parameters with different types', () => {
+    const a = of(1);
+    const b = of('a');
+    const c = of(true);
+    const d = of([1, 2, 3]);
+    const e = of(['blah']);
+    const o = race([a, b, c, d, e]); // $ExpectType Observable<string | number | boolean | number[] | string[]>
+  });
+
+  it('should support 6 or more parameters of the same type', () => {
+    const a = of(1);
+    const o = race([a, a, a, a, a, a, a, a, a, a, a, a, a, a]); // $ExpectType Observable<number>
+  });
+
+  it('should return {} for 6 or more arguments of different types', () => {
+    const a = of(1);
+    const b = of('a');
+    const c = of(true);
+    const d = of([1, 2, 3]);
+    const e = of(['blah']);
+    const f = of({ foo: 'bar' });
+    const o = race([a, b, c, d, e, f]); // $ExpectType Observable<{}>
+  });
 });
 
-it('should handle an array of observables', () => {
-  const a = of(1);
-  const b = of(2);
-  const o = race([a, b]); // $ExpectType Observable<number>
+it('should race observable inputs', () => {
+  const o = race(of(1), Promise.resolve('foo'), [true, false]); // $ExpectType Observable<string | number | boolean>
 });
 
-it('should return {} for array of observables of different types', () => {
-  const a = of(1);
-  const b = of('test');
-  const o = race([a, b]); // $ExpectType Observable<{}>
+it('should race an array observable inputs', () => {
+  const o = race([of(1), Promise.resolve('foo'), [true, false]]); // $ExpectType Observable<string | number | boolean>
 });
diff --git a/src/internal/observable/race.ts b/src/internal/observable/race.ts
index 7a1015c02f..c2c178c6d6 100644
--- a/src/internal/observable/race.ts
+++ b/src/internal/observable/race.ts
@@ -4,22 +4,31 @@ import { fromArray } from './fromArray';
 import { Operator } from '../Operator';
 import { Subscriber } from '../Subscriber';
 import { Subscription } from '../Subscription';
-import { TeardownLogic } from '../types';
+import { TeardownLogic, ObservableInput } from '../types';
 import { OuterSubscriber } from '../OuterSubscriber';
 import { InnerSubscriber } from '../InnerSubscriber';
 import { subscribeToResult } from '../util/subscribeToResult';
 
 // tslint:disable:max-line-length
-export function race<A, B>(a: Observable<A>, b: Observable<B>): Observable<A> | Observable<B>;
-export function race<A, B, C>(a: Observable<A>, b: Observable<B>, c: Observable<C>): Observable<A> | Observable<B> | Observable<C>;
-export function race<A, B, C, D>(a: Observable<A>, b: Observable<B>, c: Observable<C>, d: Observable<D>): Observable<A> | Observable<B> | Observable<C> | Observable<D>;
-export function race<A, B, C, D, E>(a: Observable<A>, b: Observable<B>, c: Observable<C>, d: Observable<D>, e: Observable<E>): Observable<A> | Observable<B> | Observable<C> | Observable<D> | Observable<E>;
+export function race<A>(arg: [ObservableInput<A>]): Observable<A>;
+export function race<A, B>(arg: [ObservableInput<A>, ObservableInput<B>]): Observable<A | B>;
+export function race<A, B, C>(arg: [ObservableInput<A>, ObservableInput<B>, ObservableInput<C>]): Observable<A | B | C>;
+export function race<A, B, C, D>(arg: [ObservableInput<A>, ObservableInput<B>, ObservableInput<C>, ObservableInput<D>]): Observable<A | B | C | D>;
+export function race<A, B, C, D, E>(arg: [ObservableInput<A>, ObservableInput<B>, ObservableInput<C>, ObservableInput<D>, ObservableInput<E>]): Observable<A | B | C | D | E>;
+export function race<T>(arg: ObservableInput<T>[]): Observable<T>;
+export function race(arg: ObservableInput<any>[]): Observable<{}>;
+
+export function race<A>(a: ObservableInput<A>): Observable<A>;
+export function race<A, B>(a: ObservableInput<A>, b: ObservableInput<B>): Observable<A | B>;
+export function race<A, B, C>(a: ObservableInput<A>, b: ObservableInput<B>, c: ObservableInput<C>): Observable<A | B | C>;
+export function race<A, B, C, D>(a: ObservableInput<A>, b: ObservableInput<B>, c: ObservableInput<C>, d: ObservableInput<D>): Observable<A | B | C | D>;
+export function race<A, B, C, D, E>(a: ObservableInput<A>, b: ObservableInput<B>, c: ObservableInput<C>, d: ObservableInput<D>, e: ObservableInput<E>): Observable<A | B | C | D | E>;
 // tslint:enable:max-line-length
 
-export function race<T>(observables: Observable<T>[]): Observable<T>;
-export function race(observables: Observable<any>[]): Observable<{}>;
-export function race<T>(...observables: Observable<T>[]): Observable<T>;
-export function race(...observables: Observable<any>[]): Observable<{}>;
+export function race<T>(observables: ObservableInput<T>[]): Observable<T>;
+export function race(observables: ObservableInput<any>[]): Observable<{}>;
+export function race<T>(...observables: ObservableInput<T>[]): Observable<T>;
+export function race(...observables: ObservableInput<any>[]): Observable<{}>;
 
 /**
  * Returns an Observable that mirrors the first source Observable to emit an item.
@@ -50,7 +59,7 @@ export function race(...observables: Observable<any>[]): Observable<{}>;
  * @name race
  * @owner Observable
  */
-export function race<T>(...observables: (Observable<any>[] | Observable<any>)[]): Observable<T> {
+export function race<T>(...observables: ObservableInput<any>[]): Observable<T> {
   // if the only argument is an array, it was most likely called with
   // `race([obs1, obs2, ...])`
   if (observables.length === 1) {